Myna assemblages 1992

Biovigyaiiam, 18(2): 1 16-1 18, 1992

Diurnal Intra- and Interspecific
Assemblages of Indian Mynas

Several birds have tendencies of gathering
or assembling together either in the feeding
arenas during daytime or at communal
roosts at nignt. Number of workers such
as Lister (1954 a and b), Murton (1971).
Zahavi (1971), Ward and Zahavi (1973),
Gadgil and Ali (1975), Gadgil (1976),. have
pointed out such assemblages of birds with
their probable functions. Counsilman
(1974) while studying the waking and roost-
ing behaviour of Indian Mynas in Atikland,
New Zealand has slated their significance
■/-'.-:. of gathering before roosting. > ,; i ,,K.hc,i;a ,aj_id :
Kalsi (1986) have also indicated the Impor-
tance of gathering before roosting and
mixed roosts while studying the roosting
behaviour of Bank Mynas. The omni-
vorous bird like the Indian Myna, Acrido-
tlieres trislis (Linnaeus) [Sturnidae: P,asscri-
formes] exhibits this tendency of gathering
or gregariousness.

The present note deals with observations
on the assemblages of Indian Mynas with
individuals of their own species (intraspecific)
as well as with other species of birds (inter-
specific) at various times of the day. ..The
study was carried out in Pune (18° 33'N
and 73°53'L), Maharashtra during the
years 1974-1980.

Intraspecifiic Assemblages —The daily
activities of mynas start at dawn. They
leave the roost in the morning and disperse
into their feeding arenas by choosing some
directional routes. While following these
routes, mynas gathered in groups between
20 and 180 on trees (may be termed as
'halting points '). hall for- some time and
then fly on to the next halting point.

During mid-day, solitary and paired
mynas from neighbouring areas ■ were

observed to assemble (8 to 30 in numbers)
on sonic trees such as Mango (Afagnifera
indica), Tamarind {JTumarindus indica),
Coconut (Cocus nucifcra), Neem (Azadi-
recta indica), and Banyan (Ficus benga-
lensis). Such mid-day assemblages have
been termed as " secondary roosts " by
Ward and Zahavi (1973), where mynas
take a afternoon-nap. preen themselves
and make a low-pitched communal noise.
Number of such secondary roosts were
noticed in and around the city thro-
ughout the year and repeatedly year after
year. ,

Mynas start their roostward journey in
the late afternoon. The stationary mynas
; W the 'ground or on the trees were often
observed to join a flock flying overhead
while returning to the roost. The attraction
thus generated by flying flocks increases
with the size of the (lock. The flocks of
mynas begin to arrive and gather in the
vicinity of the roost in the evening. They
build up their strength (this may vary from
50 to 1000) before flying into the communal
roost; but this behaviour was not noticed
in their breeding season during April to
July. Counsilman (1974) has also inferred
that a gathering of Indian Mynas before
roosting is essentially a large and fairly
stationary flock. Further, Khera and Kalsi
(1986), have pointed out that during non-
breeding season, the Bank Mynas Acrido-
tlieres ginginianus congregate in large num-
bers before roosting, however, such gather-
ing docs not take place in the breeding
season.

Ultimately, mynas return to their com-
munal roosts in the late evening for
communal night sleep. They were noticed
to roost at 12 permanent communal roost
in Pune city where congregations of mynas
varied from 100 to 10.800 at a time.

lie

DIUkNAL ASSEMBLAGES OF INDIAN MYNAS

117

Interspecific Assemblages — During the
fruiting season of Banyan trees (Ficus
bengalensis), the number of mynas were
found to assemble together with a number
of other species of birds to exploit the fig
fruits and insects thereby. The total
number of birds at such assemblages at
any one time ranged between 20 and 200
birds of different species (Mahabal,
1977).

Such interspecific assemblages of mynas
were also observed on trees like Silk Cotton
(Salmalia malabaricum) and Flame of Forest
{Butea monospermci) which blooms in the
months of February to April. Various
species of birds visited these trees regularly
in the morning and often in the afternoon
for nector feeding. The bird species other
than Indian Mynas were mainly Brahminy
Myna, Stumus pagodarwn (Gmelin); Rosy
Pastor, Sturnus roseus (Linnaeus); Jungle
Myna, Acridotheres fuscus (Wagler); Red-
vented Bulbul, Pycnonotus cafer (Linnaeus);
and Crimsonbreasted Barbet, Megalaima
haemacephala (P.L.S. Miiller). The birds
such as Black Drongo Dicrurus ads'unilis
(Bechstein) and House Sparrow, Passer
domesticus (Linnaeus) visited these '.rees
to catch the insects disturbed by movements
of other birds. House Crow Corvus splen-
dens Vieillot and Roseringcd Parakeet
Psittacula krameri (Scopoli) were occa-
sionally noticed to feed on petals of these
flowers. Further, it was noticed that the
flocks of various species of mynas and Rosy
Pastors visit these trees by rotation. When
flocks of two different species of mynas
arrived at the same time, interspecific inter-
actions < (pushing, threatening each other
by making harsh noise, direct attack or
chasing) were observed, in which Indian
Mynas were found to be the most aggressive
species.

Besides these crowded assemblages on
trees, some sparse associations of m^rias
were also seen commonly with the bltds
such as Pond Heron, Ardcolu grayii (Sykes);
Cattle Egret, Dubulcus ibis (Linnaeus); Little
Egret, Egretta garzetta (Linnaeus); and
Redwattled Lapwing Vanellus indicus
(Boddaert) on river beds, by the side of
nallas and in agricultural fields during
daylime. Blue Rock Pigeon Columba Uvia
Gmelin, Indian Koel Eudynamys scolopacea
(Linnaeus), Brahminy Myna and House
Sparrow were noticed regularly with Indian
Mynas on roof tops of buildings and on
T.V. antennas.

Indian Mynas were also observed to form
nocturnal mixed communal roosts with
other species of birds such as Pond Heron,
Cattle Egret, Little Egret, Roseringed Para-
keet, Brahminy Myna, Rosy Pastor, Jungle
Myna and House and Jungle Crow, cither
seasonally or throughout the year.

The formation of intraspecific assemblages
of Indian Mynas during daytime and at
night strongly indicate that they possess
tendency of gathering or gregariousness.
This tendency of gathering is not only
observed at the level of intraspecific but
also at interspecific level as mynas were
noticed to form mixed flocks during day-
time while exploiting the food and mixed
roosts at night. Ward and Zahavi (1973)
have suggested that bird assemblages have
been evolved primarily for the efficient
exploitation of unevenly distributed food
sources by serving as " information-centres."
Counsilman (1974) has stated that gathering
before roosting provide protection from
predators and communal sleeping protects
Indian Mynas more from predators than
if they slept solitarily. Khera and Kalsi
(1986) believed that protection from pre-
dators and an efficient anti-predator mccha-

118

MaHabal

nism are the functions of pre-roost gathering
and mixed roosts in Bank Mynas respec-
tively. Likewise, it is possible that intra-
and interspecific assemblages of Indian
Mynas increase the awareness of individual

birds and thus afford
protection.

High A hi tuck Zoology

Field Station
Zoological Survey of India

Solan 173 212, India

some kind of
Anil Mahabal

REFERENCES

Counsilman, J. J. 1974. Waking and roosting
behaviour of the Indian Myna. num., 74:
135-148.

Gadgil, M. 1976. On mixed species assemblages. of
birds. Newsletter jor Birdwatchers, 16(3): 6-7.

Gadgil, M. & Ali, Salim 1975. Communal roost-
ing habits of Indian birds. J. Bom. not. Hist.
Soc, 72:716-727.

Kiiera, S. & KaLSI, R. S. 1986. Waking and
roosting behaviour of the Bank Myna, Acrido-
thtrcs ginginianus, in Chandigarh, and surround-
ing areas. Pavo., 24: 55-68.

Lister, M. D. 1954(a). Some bird associations of
Indian cultivated and waste lands. J. Bom-
not. Hist. Soc, 51: 19-28.

Lister, M. D. 1954(b). Some bird associations of
Indian built up areas. J. Bom. nnt. Hist. Soc,
51:369-377.

Mahabal, Anil 1977. Interspecific assemblages
of birds. Newsletter Jor Birdwatchers, 17(6): 5.

Murton R. K. 1971. Why do some bird species
feed in flocks ? Ibii., 113: 534-536.

Ward, P, & Zahavi, A. 1973. The importance of
certain assemblages of birds as "information-
centres" for food finding. Ibis., 115: 517-534.

Zaiiavi, A. '971. The function of pre-roost gather-
ings and communal roosts. Ibis., 113; 106-109.

(.Received September 20, 1991 ; revised June 26, 1992)